The present invention relates to a vehicular display system mounted on a vehicle such as an automobile and more particularly to a vehicular display system for displaying data concerning a vehicle such as vehicle speed, engine revolutions, time and various warnings.
As a display system of this type there has heretofore been known such a display system as disclosed in Japanese Utility Model Laid-Open Publication No. 48576/75, which is shown in FIG. 1. In this known display system, a projective display unit (not shown) comprising a lens, a display device disposed within the focus of the lens and a case which houses those components therein, is mounted inside an instrument panel 1b located in front of a steering wheel 1a of a vehicle 1, and on a dash board 1c located in front of the instrument panel 1b is disposed a half mirror at a predetermined angle relative to the above lens, the half mirror 2 having predetermined transmissivity and reflectivity. A display image which represents a data concerning the vehicle such as, for example, vehicle speed displayed on the above display device is projected on the half mirror 2 through an opening 1d formed in the dash board 1c, whereby a virtual image 3 is formed at a predetermind distance ahead of the half mirror 2.
Consequently, the driver on the driver's seat sees the virtual image 3 in an overlapped state with the external sight and thus can obtain data required for driving without taking his eyes off the external sight, thereby permitting a safe driving of the vehicle.
By the way, the vehicle driving is performed by drivers of various constitutions or having various habits, so the line of vision for the outside greatly differs depending on drivers during vehicular driving. In this case, by making pivotable a mounting base end of the half mirror 2 onto the dash board 1c, the half mirror 2 can be adjusted to a suitable position, that is, the position of the virtual image 3 can be moved up and down for alignment with the line of vision of the driver.
However, the movable range of the virtual image 3 is restricted by the size of the half mirror 2, so where it is to cover all drivers, it becomes necessary to use the half mirror 2 having a correspondingly larger area.
But, if the half mirror 2 is made very large, the greater part of the driver's front sight will be covered with the same mirror, thus resulting in that the driver sees the front through the half mirror 2. Although the half mirror 2 is a see-through mirror, it is apparent that this mirror will be a hindrance to the driver's front sight. Besides, it exerts a bad influence upon the design of the instrument panel 1b and obstructs wiping of a front glass le behind the panel. Additionally, there is a serious problem also from the aspect of safety because an upper edge of the half mirror 2 faces the driver's side.
The present invention has been accomplished in order to solve the above-mentioned problems.